Our objectives are to continue the formulation of quantitative structure-active relationships (QSAR) from published data in the literature and from enzyme-ligand interactions obtained in our laboratory. In this way we plan to enlarge the type of biosystems and type of compounds for which QSAR can be employed. A by-product of this work will be a great increase in the size of our computerized bank of drug, bioactivities and equations. We plan to study this data base with the aim of developing generalizations about the kind of activity produced by various pharmacophores in different biosystems. We plan to continue to collect, measure, evaluate, organize, and publish physiochemical parameters necessary to advance QSAR. We plan to study ligand interaction with three enzymes whose x-ray structures are known in order to develop techniques for producing highly selective inhibitors. Those techniques would then be used to design better antitumor and antibacterial drugs. We plan to attempt to improve our general QSAR model by studying the nonlinear models recently proposed by Martin and Kubinyi.